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首页> 外文会议>7th Spacecraft Charging Technology Conference 2001: a Spacecraft Charging Odyssey, Apr 23-27, 2001, Noordwijk, the Netherlands >A Survey of Spacecraft Charging Events on the DMSP Spacecraft in LEO
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A Survey of Spacecraft Charging Events on the DMSP Spacecraft in LEO

机译：LEO DMSP航天器上的航天器充电事件调查

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The DMSP satellites orbit the Earth at ～ 840 km and carry various instruments for sensing the space environment. They provide the ideal platform from which to investigate spacecraft charging in low-earth orbit (LEO). We have searched 12 years of DMSP satellite data, 1989 - 2001, for events in which the spacecraft frame charged to more than 100 V negative. We found 1253 events, all associated with an intense energetic electron precipitation event (an auroral arc) within a region of very low plasma density in the auroral zone. The occurrence frequency of events was highly correlated with solar activity with the preponderance of events occurring near solar minimum; indeed, no events were found during the peak the last solar cycle in 1989 - 1990. There was a strong hemispherical asymmetry with almost 80% of the events occurring in the southern hemisphere due to the seasonal relationship of the spacecraft orbital plane and the Earth's spin axis. There was a strong seasonal dependence with all of the events centered around winter solstice and none occurring at summer solstice due to solar illumination. During solar minimum, the plasma density was three orders of magnitude or more less than the density at solar maximum. During solstice, the density was up to three orders of magnitude less in the winter hemisphere than in the summer hemisphere. The currents associated with precipitating electrons in an auroral arcs are usually much smaller that the currents from the in situ plasma. However, the plasma density can be low enough at DMSP altitudes that the currents from precipitating electrons dominate, driving the spacecraft potential negative. We have shown that these conditions exist a significant fraction of the time, particularly in the southern hemisphere at winter solstice, such that high-level charging events occur almost daily on the DMSP spacecraft.
机译：DMSP卫星在约840 km处绕地球运行，并携带各种用于感知空间环境的仪器。它们为研究低地球轨道（LEO）的航天器充电提供了理想的平台。我们已经搜索了1989年至2001年的12年DMSP卫星数据，以寻找航天器机壳带负电超过100 V的事件。我们发现了1253个事件，都与极光区域中血浆浓度极低的区域内发生的高能电子沉淀事件（极光弧）有关。事件的发生频率与太阳活动高度相关，在太阳极小值附近发生的事件占多数。实际上，在1989年至1990年的最后一个太阳周期的峰值期间未发现任何事件。由于航天器轨道平面和地球自转的季节性关系，南半球发生了强烈的半球不对称性，其中近80％的事件发生在南半球轴。强烈依赖于季节，所有事件都集中在冬至左右，而夏至没有发生，因为太阳光照。在太阳最小时，等离子体密度比太阳最大时的密度小三个数量级或更多。在冬至期间，冬季半球的密度比夏季半球的密度低三个数量级。与极光弧中的电子沉淀相关的电流通常比原位等离子体的电流小得多。但是，在DMSP高度，等离子体密度可能足够低，以至于来自沉淀电子的电流起主导作用，使航天器的电势为负。我们已经表明，这些条件存在的时间要占很大一部分，尤其是在冬至时在南半球，这样高水平的充电事件几乎每天都会在DMSP航天器上发生。

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